PubMed abstract / permitted excerpt

Nature, Published online: 02 September 2026; doi:10.1038/d41586-026-02694-z At birth, the brain contains its own immune cells, called microglia, that are thought to persist throughout life without being replaced by cells from outside the brain. Studies that trace cell lineage now show that these cells are replaced by circulating immune cells during ageing, revealing a previously unappreciated inte